Audio system



FIG. 1 is a perspective view of an audio system as seen from the front, top and right side;

FIG. 2 is a perspective view thereof as seen from the back, top and left side; and,

FIG. 3 is a top view thereof.

The dotted line portions of the drawings represent environmental structure only and form no part of the claimed design. The broken line showing of numbers, words, and symbols forms no part of the claimed design. 

CLAIM The ornamental design for an audio system, substantially as shown and described. 